In U.S. Pat. No. 6,369,952, a visual display device is provided for delivering a generated image, preferably combinable with environment light, to the eye of a user. A shroud protects from stray light and holds optical elements in desired alignment. An image generator is masked by at least two masks to provide for a high quality image without waste. A removably mounted shield or activatable device and convert the apparatus from a see-through device to an immersion device and back again. The device can be mounted to the user's head while still allowing for use of conventional eyeglasses. A tracker for outputting an indication of the orientation, attitude and/or position of a head-mounted display (HMD) may be provided. The tracker can be configured so that it is incorporated in the HMD housing and/or can be easily decoupled from the HMD, so that the HMD can be used without the tracker (e.g. for watching movies).
In U.S. Pat. No. 6,611,385, a wearable display system including a display panel to display a signal processed in a predetermined way. The wearable display system includes a grating to diffract a signal output from the display panel, a waveguide to guide the propagation of a signal diffracted by the grating; and a magnifying lens to magnify the signal propagating through the waveguide and to direct the signal toward an eye of a user. The waveguide is formed by a combination of two or more substrates. According to the wearable display system, optical devices are easily and simply arranged on the waveguide to conform to specifications, and furthermore, are individually manufactured and attached to the waveguide. Therefore, the wearable display system is manufactured with minimum time and effort.
In U.S. Pat. No. 5,991,084, a compact virtual image display system is provided, which includes a microdisplay; a first magnification optic consisting of three surfaces: a display input surface; a reflective/transmissive surface, and a reflective first magnification element surface; and a second magnification optic. Light forming the source object enters the first magnification optic at the display input surface. The light travels within the first magnification optic such that it is projected to an area on the reflective backslash transmissive surface that is at least partially within the full field of view provided by the second magnification optic. The light is directed to the reflective/transmissive surface at a first angle relative to the reflective/transmissive surface such that the light is internally reflected by the reflective/transmissive surface and directed to the reflective first magnification element surface. The first magnification element surface internally reflects the light corresponding to the source object as a magnified virtual image. The magnified virtual image is then is conveyed within the first magnification optic back to the reflective/transmissive surface at a second angle of incidence relative to the reflective/transmissive surface such that the light is transmitted by the reflective/transmissive surface out of the first magnification optic. The second magnification optic is positioned to receive the magnified virtual image transmitted from the first magnification optic and transmit a compound magnified virtual image of the magnified virtual image of the source object to the observer.
In U.S. Pat. No. 6,683,584, a camera display system displays information via a matrix display element mounted within a housing that is positioned relative to at least eye of a user. The display is connected to a video or image sensor such that the user can view information or images shown on the display. The display can be mounted to a housing so that the user can move the display in and out of the user's field of view.
In U.S. Pat. No. 6,680,802, a one-eye viewing type head-mounted image display device that is compact and comfortably wearable consists mainly of a viewer and an elastic member. The viewer includes an LCD, a main prism, a see-through prism, a frame, and a microphone. The main prism conducts an image, which is displayed on the LCD, to make the image viewable with either the user's right eye or left eye. The see-through prism is bonded to the main prism, transmits extraneously light, and conducts the light to a users eye. The frame bears the LCD at a predetermined position relative to the prisms. The microphone is mounted in the frame. The elastic member includes a nose rest which supports the viewer so that the viewer will be located at a predetermined position in front of the user's eye.
However, all above mentioned prior arts only disclose optical systems or mechanic structures for displaying image to the head mounted display, but no prior art discusses or discloses any structure or mechanism about the image quality to the eyes. Many people have eye diseases, such as far-sightedness (hyperopia), nearsightedness (shortsightedness; myopia), weak sight (amblyopia), or astigmatism, which cannot see clear views for normal images. Thereby, as a normally clean image is displayed on a head mounted unit, the image is vague to the eye-diseased user. This is because it is not imaged in the focus of the user. For example, the image of a nearsighted people is focused before the retina so that the people will see a vague image. For example, nearsighted people must wear a pair of eyeglasses to adjust the image clearness to make the image is just imaged on the retina. However, this problem is also occurred for the people wearing a head mounted display since in general, the user wearing a head mounted display can not further wear a pair of glasses Thus, it is necessary that the image displayed on the head mounted display can provide images suitable for the eyes of the user. Thus it is necessary to that the images displayed on the head mount display is adjusted in advance so that as the image is incident in to the eyes it present a clear image on the retina of the user's eyes.
Moreover, a further application is that a head mounted display can be used to completely replace the function of eyeglasses, especially, for patients of weak sights. That, images are captured through a camera and then the images are processed in advance so as to display on the display screen which can present clear images to the user. Thereby, it is necessary to process the captured images in advance. However, all the prior arts cannot provide these functions to users.